1. Field of Art
This invention relates generally to charging of electrified vehicles, and more particularly to portable DC charging devices.
2. Background Art
In conventional and hybrid electric automobiles, an internal combustion engine can provide motoring power, and a low voltage battery can provide power for devices such as a starter motor, a cabin ventilation system, internal and external lights, an entertainment system and the like. In general, with a gasoline-powered engine a vehicle with full fuel reservoir can drive around 300 or more miles. When the fuel supply for the engine is depleted, it can be replenished with a brief stop at a service station. In desperate circumstances, when a vehicle is stranded without fuel in a remote area, a simple hose can be used to siphon gasoline from the fuel tank of an accommodating passing motorist who stops to assist. Similarly, when the charge of a conventional low voltage automobile battery drops below a required minimum, rendering a vehicle inoperable, the battery voltage can usually be boosted without too much difficulty or delay. For example, a set of inexpensive jumper cables, easily stowed at the vehicle, can electrically connect terminals of a functional battery to those of a depleted battery to complete a charging circuit that can reenergize the dead battery.
While a majority of automobiles continue to employ a gasoline engine, a quest to reduce emissions and increase exploitation of renewable energy drives an expanding market for electrically powered automobiles. Fully electrified vehicles that rely on a high voltage battery for motoring power have a driving range of around 100-200 miles per full charge. A high voltage battery is typically recharged by connection with an alternating current (AC) power grid. In most cases, a high voltage battery is coupled to the grid over an extended period during which there is no demand for the vehicle, such as during working hours, overnight at home, or during a prolonged parking period at a public charging station, such as at an airport while an operator is on travel.
For long-range travel, an operator can often plan a route and itinerary to include stops of sufficient duration at known recharging site locations. Should a battery unexpectedly run low during a motoring excursion, due, for example, to unexpected headwinds or other environmental factors that increase the amount of energy required for motoring, it is possible to recharge it at a charging station en route so that an operator can continue driving to his intended destination. One potential problem with such a scenario, however, is that charging stations for electrified vehicles are generally not as ubiquitous or conveniently located as conventional gasoline stations. Consequently, the likelihood of encountering one when a battery charge unexpectedly runs low is much less than that of happening upon a conventional service station.
Most charging stations provide lower power Level 1 or Level 2 charging by a process that can take up to several hours to charge a depleted battery. While long charging times can be acceptable when charge transfer is performed at predetermined times and locations, an extended recharging period can adversely affect travel plans when the process must be conducted unexpectedly. Concern regarding the possibility that a battery will become depleted while driving can discourage consumers from purchasing or employing electrified vehicles, depriving them personally, and the society at large, of the many benefits that an electric vehicle can offer.